Tuesday, August 25, 2009

Has Gaia got over her hissy fit?

 Saharan oasis

In a startling about turn, James Lovelock CBE, CH, FRS produced a book not so long ago with the title "Revenge of Gaia". He had previously presented  Gaia as a  benign guardian presence, a quasi-religious one some might say.  Gaia - the totality of life on Earth, behaves as a gigantic single organism, in which its numerous parts function cooperatively  when confronted with threatening change to ensure the survival of the total.  Lovelock then suddenly jumped aboard the alarmist bandwagon, having become an AGW true-believer.  We're doomed, he said, we're all doomed  I tell you.  Why?  Because we've foolishly pushed up the level of CO2 so fast with our wanton burning of fossil fuel that poor old Gaia was now in a right tiz-woz.

Some of us questioned whether things were really so bad. According to the Gaia idea, a change like, say,  increasing CO2 or average global temperature would provoke changes in one or more life-forms that tend to restore the status quo. In other words, a variety of subtle  feedback control mechanisms come into play, maintaining homeostasis.  Thus increased CO2 would tend to stimulate plant growth . There is abundant experimental evidence:  levels of the gas are increased in some greenhouses to stimulate growth and yields. A CO2-boosted increase in photosynthesis would result in an increase in  total planetary biomass, thus tending to restore CO2 levels to their original levels.

Well, a report has just appeared on the BBC's site today, with evidence for just such an adaptive change. The treeline in the world's hills and mountains, especially in the northern hemisphere it seems,  has been creeping higher and higher. This is believed to be a response to warmer winter temperatures. More trees means more photosynthesis, more biomass, less atmospheric CO2 - other things being equal.

Now here's a strange and serendipitous thing. Having mentally composed the above, I got to wondering what further adaptive change might occur  - one that might have an even more dramatic effect. I found myself thinking about those vast bare expanses of the Sahara, and wondering yet again why that desert gets so little rainfall.  Googling was not terribly informative, with vague references to planetary wobble, orbital precession, climate cycles bla bla.  But there was gold-dust in that list of returns. On the last day of last month (July) a report appeared claiming that the Sahara is again greening up - in Sudan, the Sahel and other regions that have been parched in recent times.

So, far from being in vengeful mood, dear old Gaia seems to be doing exactly what her proponent originally proposed. Oh ye of little faith, Professor Lovelock. Admit it - you thought your old girl had given up on us...

Further reading:   Rowena Mason  in the Telegraph ("Carbon capture etc").

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